SERVER-37616 tuneable range deleter batch size

(cherry picked from commit 9bd063b1409d7be2e164911a4d90f1aba5864715)

3 files changed, 25 insertions, 4 deletions

diff --git a/src/mongo/db/s/collection_range_deleter.cpp b/src/mongo/db/s/collection_range_deleter.cpp
index 3b573395c57..95ae8282374 100644
--- a/src/mongo/db/s/collection_range_deleter.cpp
+++ b/src/mongo/db/s/collection_range_deleter.cpp
@@ -62,6 +62,14 @@
 
 namespace mongo {
 
+MONGO_EXPORT_SERVER_PARAMETER(rangeDeleterBatchSize, int, 0)
+    ->withValidator([](const int& newVal) {
+        if (newVal < 0) {
+            return Status(ErrorCodes::BadValue, "rangeDeleterBatchSize must not be negative");
+        }
+        return Status::OK();
+    });
+
 MONGO_EXPORT_SERVER_PARAMETER(rangeDeleterBatchDelayMS, int, 20)
     ->withValidator([](const int& newVal) {
         if (newVal < 0) {
@@ -108,6 +116,13 @@ boost::optional<Date_t> CollectionRangeDeleter::cleanUpNextRange(
     int maxToDelete,
     CollectionRangeDeleter* forTestOnly) {
 
+    if (maxToDelete <= 0) {
+        maxToDelete = rangeDeleterBatchSize.load();
+        if (maxToDelete <= 0) {
+            maxToDelete = std::max(int(internalQueryExecYieldIterations.load()), 1);
+        }
+    }
+
     StatusWith<int> wrote = 0;
 
     auto range = boost::optional<ChunkRange>(boost::none);
diff --git a/src/mongo/db/s/collection_range_deleter.h b/src/mongo/db/s/collection_range_deleter.h
index d6631cdcf26..4949c1febde 100644
--- a/src/mongo/db/s/collection_range_deleter.h
+++ b/src/mongo/db/s/collection_range_deleter.h
@@ -44,6 +44,12 @@ class BSONObj;
 class Collection;
 class OperationContext;
 
+// The maximum number of documents to delete in a single batch during range deletion.
+// secondaryThrottle and rangeDeleterBatchDelayMS apply between each batch.
+// Must be positive or 0 (the default), which means to use the value of
+// internalQueryExecYieldIterations (or 1 if that's negative or zero).
+extern AtomicInt32 rangeDeleterBatchSize;
+
 // After completing a batch of document deletions, the time in millis to wait before commencing the
 // next batch of deletions.
 extern AtomicInt32 rangeDeleterBatchDelayMS;
@@ -166,13 +172,15 @@ public:
      * If it should be scheduled to run again because there might be more documents to delete,
      * returns the time to begin, or boost::none otherwise.
      *
+     * Negative (or zero) value for 'maxToDelete' indicates some canonical default should be used.
+     *
      * Argument 'forTestOnly' is used in unit tests that exercise the CollectionRangeDeleter class,
      * so that they do not need to set up CollectionShardingState and MetadataManager objects.
      */
     static boost::optional<Date_t> cleanUpNextRange(OperationContext*,
                                                     NamespaceString const& nss,
                                                     OID const& epoch,
-                                                    int maxToDelete,
+                                                    int maxToDelete = 0,
                                                     CollectionRangeDeleter* forTestOnly = nullptr);
 
 private:
diff --git a/src/mongo/db/s/metadata_manager.cpp b/src/mongo/db/s/metadata_manager.cpp
index bf47163ee29..e1771c7b70b 100644
--- a/src/mongo/db/s/metadata_manager.cpp
+++ b/src/mongo/db/s/metadata_manager.cpp
@@ -149,11 +149,9 @@ void scheduleCleanup(executor::TaskExecutor* executor,
             auto uniqueOpCtx = Client::getCurrent()->makeOperationContext();
             auto opCtx = uniqueOpCtx.get();
 
-            const int maxToDelete = std::max(int(internalQueryExecYieldIterations.load()), 1);
-
             MONGO_FAIL_POINT_PAUSE_WHILE_SET(suspendRangeDeletion);
 
-            auto next = CollectionRangeDeleter::cleanUpNextRange(opCtx, nss, epoch, maxToDelete);
+            auto next = CollectionRangeDeleter::cleanUpNextRange(opCtx, nss, epoch);
             if (next) {
                 scheduleCleanup(executor, std::move(nss), std::move(epoch), *next);
             }